Chain saw



H. DEELMAN Sept. 5, 1967 CHAIN SAW Filed Deb. v, 1964 IN VEN TOR BY HA Y0 .DEEL MA A w 4% v 4& A 7' TOE/V675 United States Patent 3,339,596 CHAIN SAW Hayo Deelman, Peterborough, Ontario, Canada, assignor to Outboard Marine Corporation, Waukegan, 111., a corporation of Delaware Filed Dec. 7, 1964, Ser. No. 416,491 Claims. (Cl. 143-32) The invention relates generally to chain saws.

The invention serves to reduce wear on a chain saw cutter bar and on the links of a saw chain by cushioning the delivery of power from the engine to the saw chain. In accordance with the invention, resilient driving means are provided intermediate the engine and the chain sprocket which drives the saw chain. Many present date chain saws include centrifugal clutches for releasably connecting the sprocket and the engine crankshaft. Preferably, the resilent driving means is integrated with the centrifugal clutch.

Other objects and advantages of the invention are set forth in the following description and accompanying drawings in which:

FIGURE 1 is a perspective view of a chain saw embodying various of the features of the invention;

FIGURE 2 is an enlarged, fragmentary view of one embodiment of a resilient drive which is especially adapted for incorporation in the chain saw shown in FIGURE 1 and which embodies various of the features of the invention;

FIGURE 3 is a sectional view taken line 33 of FIGURE 2;

FIGURE 4 is an enlarged fragmentary sectional view of another embodiment of a resilient drive which is especially adapted for incorporation in the chain saw shown in FIGURE 1 and which embodies various of the features of the invention;

FIGURE 5 is a fragmentary sectional view taken generally along line 5-5 of FIGURE 4;

FIGURE 6 is a fragmentary end elevational view of a third embodiment of a resilient drive which is especially adapted for incorporation in the chain saw shown in FIGURE 1 and which embodies various of the features of the invention;

FIGURE 7 is a fragmentary side elevational view of one of the components of the resilient drive shown in FIGURE 6;

FIGURE 8 is a fragmentary sectional view taken generally along line 8-8 of FIGURE 6; and

FIGURE 9 is a fragmentary sectional view taken generally along 9-9 of FIGURE 8.

Shown in the drawings is a chain saw 11 including a prime mover in the form of an internal combustion engine 13 having a crankshaft 15 (see FIGURE 3) suitably supported for rotation, a cutter bar 17 (see FIGURE 1) supporting a saw chain 19 trained about a sprocket 21, and a drive means 23 which connects the crankshaft or driving member 15 and the chain sprocket or driven member 21 and includes a resilient connection. Various resilient drive means can be employed. FIGURES 2 and 3 are illustrative of one embodiment of a resilient drive in accordance with the invention.

In FIGURE 2, the resilient drive means 23 is integrated with a centrifugal clutch 25 which connects the crankshaft 15 with the chain sprocket 21 and which is rotatably mounted on the crankshaft 15 in a so-called direct drive arrangement. However, the invention is not limited to direct drive chain saws and is equally applicable to chain saws including speed reduction means, such as enmeshed gearing, between the engine crank shaft and the sprocket and to chain saws wherein the driving member is other than the engine crankshaft.

generally along The centrifugal clutch shown in FIGURE 3 includes an inner or driving member 27 which is keyed to the crankshaft 15 and which supports one or more weights 29 which are rockably mounted by pivot pins31. In response to rotation of the crankshaft 15, the weights 29 are pivoted outwardly to drivingly engage a clutch drum 33 which, with respect to the clutch constitutes a driven member, and with respect to the resilient drive, can be considered as constituting a driving member, and which has a hub 35 rotatably mounted on the crankshaft 15. The hub 35 on the drive shaft also constitutes means for rotatably mounting the sprocket 21 or driven member on the engine 13. The sprocket 21 is retained on the hub 35 by a snap ring 37.

The clutch drum 33 and the sprocket 21 are connected by resilient drive means 23 in the form of a disk 39 which is welded or otherwise secured to the sprocket 21 and which includes a series of prongs or lugs 41 having terminal ends projecting in a direction parallel to the axis of crankshaft rotation. The prongs 41 are respectively received in separate elastomeric cushions, inserts, or members 43, which are fabricated of rubber or like material, and which are respectively located in separate seats 45 provided in the radial face 47 of the clutch drum 33.

Receipt of the prongs 41 in the cushions 43 provides a resilient connection.

The seats 45 include side walls 49 which, together with the prongs 41, constitute means on the sprocket 21 and on the clutch drum 33 for limiting flexure of the resilient drive means or connection and for establishing direct driving engagement between the sprocket and the clutch drum. In this regard, limitation of resilient travel between the clutch drum 33 and the disk 39 is provided as the prongs 41 approach the side walls 49 of the seats 45.

During operation of the chain saw 11, the torque delivered to the sprocket 21 in response to each firing of the engine 13 is cushioned by the resilieht character of the elastomeric inserts, thereby affording smoother delivery of power to the saw chain and reducing wear between the saw chain 19 and the cutter bar 17. More specifically, assuming the crankshaft 15 to be rotating in the clockwise direction as shown in FIGURE 2, the inserts 43 permit limited angular movement of the drum 33 in the clockwise direction in advance of the sprocket 21 at the time of the engine power stroke. The extent of the angular advancement of the 'drum relative to the sprocket is limited by the approach of the prongs 41 to the side walls 49 of the seats 45.

In the embodiment shown in FIGURES 5 and 6, the resilient drive comprises an annular flange 61 which is welded or otherwise fixed to the clutch drum 33, a disk 39 welded or otherwise fixed to the sprocket 21, and cooperating means on the disk 39 and on the flange 61 affording a resilient driving connection. More specifically, spaced around the flange 61 are a series of studs 63 which are fixed to the flange 61 and extend toward the sprocket 21. The disk 39 includes an outer radially extending margin 65 projecting radially beyond the drum 33. Fixed to and extending from the margin 65 toward the flange 61 and in parallel relation to the axis of drum rotation are a series of studs 67 which are spaced in generally the same manner as the studs 63. Located intermediate the studs 67 are a series of ears or lugs 69 which are bent out of the margin 65 and project toward the flange 61 in adjacently spaced relation to the studs 63.

Connecting adjacent studs 63 and 67 are resilient members or springs 71 which include arcuate central portions 73 and looped end portions 75 encircling the adjacent studs 63 and 67. The studs 63 and 67 and the springs 71 constitute portions of a resilient driving connection or drive means. The studs 63 and the lugs 69 constitute components of means on the sprocket 21 and on the clutch drum 33 for limiting flexure of the resilient drive means and for establishing direct driving engagement between the sprocket and the clutch drum. In this regard,'limitation of the rotative movement of the clutch drum 33 relative to the sprocket 21 occurs in response to driving engagement of the studs 63 with the ears or lugs 69 incident to rotative advancement of the flange 61 and studs 63 in the counter-clockwise direction, as seen in FIGURE 5, in advance of the studs 67 of disk 39.

More specifically, assuming the drum 33 to be rotating in the counter-clockwise direction as seen in FIGURE 5, torque delivery occurring in response to each explosion in the engine 13 will serve to advance, in the counterclockwise direction, the stud 63 relative to the stud 67, thereby straightening the curved portions 73 of the springs 71, as shown in dotted outline in FIGURE 5. Such rotative advancement of the clutch drum 33 relative to the sprocket 21 and resilient flexure of the springs 71 is limited by reason of engagement of the stud 63 with the lug 69.

In the embodiment shown in FIGURES 6 and 9, the resilient drive means includes a flange 61 which is fixed to the drum clutch 33 as by welding or the like, and which has a series of studs 63 extending toward the sprocket 21 and a series of radially outwardly extending tabs 81 which are angularly offset from the studs 63 as shown in FIGURE 9. The resilient drive means also in- .cludes a disk or member 39 which is fixed to the sprocket 21 as by welding or the like, and has a dished portion 82, a radially extending margin 65, and a flange portion 83 which extends in partially telescopic relation to the clutch drum 33 radially outwardly of the studs 63.

Formed in the flange portion 83, inwardly of the free end thereof, are a series of resilient members or tabs 85 which resiliently extend arcuately inwardly from the flange portion 83 for respective engagement with the studs 63 in response to clutch drum movement in the counterclockwise direction as seen in FIGURE 6, thereby providing a resilient drive means. In operation, the ears or tabs 85 flex in response to driving engagement by the studs 63 to thereby cushion delivery of torque to the disk 39 and sprocket 21.

Also provided are means on the sprocket 21 and on the clutch drum 33 for limiting flexure of the resilient drive means and for establishing direct driving engagement between the sprocket and the clutch drum. In this regard, there is formed in the flange portion 83 at the free periphery thereof a series of recesses 87 which loosely receive the lugs 81. Angular movement of the lugs 81 in the recesses 87 serves to provide a direct driving engagement of the flange portion 83 by the lugs 63 after an initial degree of tab flexure and resultant cushioning of increasing torque delivery to the sprocket, thereby limiting angular movement of the clutch drum 33 relative to the sprocket 21 and flexure of the resilient drive means.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. The combination of a chain saw engine including a crankshaft, a cutter bar extending from said engine, a chain sprocket, means on said engine rotatably supporting said chain sprocket, a clutch having a driving member and a driven member, drive means connecting said driven clutch member and said sprocket including a resilient connection, means on said sprocket and on said driven clutch member for limiting flexure of said resilient connection, and a saw chain trained around said sprocket and said cutter bar.

2. The combination of a chain saw engine including a crankshaft, a cutter bar extending from said engine, a chain sprocket, means on said engine rotatably supporting said chain sprocket, a clutch having a driving member and a driven member, drive means connecting said driven clutch member and said sprocket including a resilient connection, means on said sprocket and on said driven clutch member for limiting flexure of said resilient connection and for establishing direct driving engagement between said sprocket and said driven clutch member, and a saw chain trained around said sprocket and said cutter bar.

3. A chain saw comprising an engine including a crankshaft, a cutter bar extending from said engine, a clutch having a driving member keyed to said crankshaft and a driven member having a hub rotatably mounted on said crankshaft, a chain sprocket rotatably mounted on said hub, driving means connecting said driven clutch member and said sprocket including a resilient connection and a saw chain trained around said sprocket and said cutter bar.

4. A chain saw comprising an engine including a crankshaft, a cutter bar extending from said engine, a chain sprocket, means on said engine for rotatably mounting said chain sprocket, means drivingly connecting said crankshaft to said chain sprocket including a resilient connection, and a saw chain trained around said sprocket and said cutter bar.

5. A chain saw comprising an engine including a crankshaft, a cutter bar extending from said engine, a clutch carried by said engine and including a driving member driven by said crankshaft and a driven member having a hub rotatably mounted coaxially with said driving member, a chain sprocket rotatably mounted on said hub, driving means connecting said driven clutch member and said sprocket including a resilient connection, and a saw chain trained around said sprocket and said cutter bar.

References Cited UNITED STATES PATENTS 735,859 8/1903 Cooper 64-27 740,445 10/ 1903 Langerfeld 64-27 1,180,695 4/1916 Carlson 54-27 1,451,576 4/ 1923 Houston 64-27 1,861,390 5/1932 Gunn 64-27 2,053,849 9/1936 Spase 64-27 X 2,371,653 3/1945 Schuckers 64-1 X 2,675,835 4/1954 Kiekhaefer 143-32 3,099,924 8/ 1963 Armstrong 74-243 3,144,890 8/1964 Irgens 143-32 FOREIGN PATENTS 175,429 2/ 1922 Great Britain. 288,457 4/ 1928 Great Britain.

DONALD R. SCHRAN, Primary Examiner.

HALL C. COE, Assistant Examiner. 

1. THE COMBINATION OF A CHAIN SAW ENGINE INCLUDING A CRANKSHAFT, A CUTTER BAR EXTENDING FROM SAID ENGINE, A CHAIN SPROCKET, MEANS ON SAID ENGINE ROTATABLY SUPPORTING SAID CHAIN SPROCKET, A CLUTCH HAVING A DRIVING MEMBER AND A DRIVEN MEMBER, DRIVE MEANS CONNECTING SAID DRIVEN CLUTCH MEMBER AND SAID SPROCKET INCLUDING A RESILIENT CONNECTION, MEANS ON SAID SPROCKET AND ON 